UNIVERSITY PARK, Pa. -- Here in the East, where most shingles are made of asphalt and people give little thought to the advantages of shingles made of cement, the significance of Penn State College of Agricultural Sciences researcher Paul Blankenhorn's work may not be obvious.

But in places like the West -- where the specter of wildfire passing from burning trees to the roofs of houses is all too common -- the benefits of fireproof coverings is obvious. But until relatively recently, cement was thought to be too weak and brittle to be used for products such as shingles and siding that must be durable and at least slightly flexible.

That is changing, however, as scientists discover ways to supplement cement with additives to make composite materials that retain cement's best properties -- fire resistance, water resistance and stability -- while contributing elasticity and crack resistance. Blankenhorn says wood seems to hold the most promise as a cement additive, and it is the medium on which he has focused.

Over eight years, the professor of wood technology has studied the effects of adding wood fiber from recycled newspaper and kraft paper (brown paper bags) to Portland cement. He has experimented with coating the wood fibers with various water soluble polymers such as acrylics, silicates and silane before they are added to the cement. Blankenhorn's work shows how cement-wood fiber composites can make lighter, stronger, flexible, more durable shingles, siding and other products.

"In our research, we did not use wood particles, but wood fibers -- the individual cells," Blankenhorn explains. "That's completely different than what has been done before -- using wood particles, such as sawdust, as an inert filler material. We tried to create a composite material that retained the best properties of both the cement and the wood."

According to Blankenhorn, some of the advantages wood fibers bring to cement-fiber composites include availability, high tensile strength, relatively high elasticity and the well-developed technology to easily extract the fibers for use in the composites.

"Europeans have been using cement products for shingles for years, as have the Japanese," says Blankenhorn. "The shortcoming of such cement products, obviously, is that they are brittle and break easily. We are trying to develop ways to make cement products stronger and more flexible. I think our research shows that cement products can be made stronger and more flexible if wood fiber is treated before being added to cement to make composites."

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EDITORS: Paul Blankenhorn can be contacted at 814-865-6972 or prb@psu.edu.

Contact: Jeff Mulhollem jjm29@psu.edu 814-863-2719 814-863-9877 fax #290